Axillary dissection is the standard treatment for breast cancer patients with positive nodes. However, seroma formation after axillary dissection remains the most common early complication to breast cancer surgery. It can delay the initiation of adjuvant therapy, predispose to wound infection, delay wound healing and has also been linked to arm lymphoedema. Based on some studies and our experience that vacuum assisted closure （VAC）is effective in complex wound failures following axillary dissection and groin dissection, we use VAC to prevent seroma formation after extensive axillary dissection. This study is aimed to evaluate the efficacy, safety and economics benefits of early VAC application on postoperative complications and wound healing after extensive axillary dissection in comparison to conventional suction drain.